xinitrc sample: better outline the default WM

Author: sip

xinitrc.sample

@@ -1,3 +1,7 @@
+# the following variable defines the session which is started if the user
+# doesn't explicitely select a session
+DEFAULT_SESSION=twm
+
 case $1 in
 xfce4)
 	exec startxfce4
@@ -14,6 +18,6 @@ blackbox)
 	exec blackbox
 	;;
 *)
-	exec twm
+	exec $DEFAULT_SESSION
 	;;
 esac